Periodontal diseases

Pathogenesis of inflammatory and dystrophic processes

The development of the pathology represents a sequential cascade of reactions in which microbial aggression is closely intertwined with the host response. The process does not occur spontaneously, but goes through a series of regular stages, each of which exacerbates the damage to the tooth's supporting apparatus.

1. Biofilm formation. The primary triggering event is always the formation of dental plaque. Microorganisms colonize the tooth surface, creating a stable community.
2. Initiation of inflammation. The presence of bacterial mass triggers a response in the surrounding tissues, which clinically manifests as gingivitis — inflammation of the gingiva without involvement of bone structures.
3. Destructive phase. As the process progresses, the destruction of collagen fibers is triggered. A crucial role at this stage is played not only by the bacteria themselves, but also by immunopathological reactions. A hyperreactive immune response leads to the resorption of the alveolar process bone (tooth socket).
4. Terminal stage. The end result of the uncontrolled inflammatory and dystrophic process is the loss of the periodontal ligament apparatus and tooth loss.

Microbiology of periodontitis: acute and chronic forms

Periodontitis is characterized by deep damage to the periodontal complex. It is extremely critical to differentiate between the acute and chronic forms of the disease, as their microbial landscape has fundamental differences. In the subgingival zone during periodontitis, filamentous and flagellated microorganisms traditionally predominate.

Acute periodontitis is associated with highly aggressive microflora capable of rapid tissue damage. This group includes:

• Aggregatibacter actinomycetemcomitans
• Eikenella corrodens
• Capnocytophaga sputigena
• Prevotella intermedia

Chronic periodontitis differs in the spectrum of dominant pathogens. The key pathogens here are Porphyromonas gingivalis, Tannerella forsythia, and Prevotella intermedia.

In addition to the main pathogens, an abundant concomitant flora is always present in the lesion focus. It includes spirochetes, peptostreptococci, various bacteroids, staphylococci, streptococci, and even enterobacteria. Such microbial diversity complicates the course of the disease and requires a comprehensive approach to sanitation.

Microflora in gingivitis and pericoronitis

Gingivitis and pericoronitis are pathologies predominantly limited to gingival tissue damage (without destruction of the socket bone). The microbial landscape in these conditions also has its own specifics.

A large number of Gram-negative and filamentous bacteria are found in the foci of gingival inflammation. Typical flora includes:

• Spirochetes and actinomycetes
• Campylobacter
• Veillonella and peptostreptococci

Among the specific species playing a leading role in maintaining soft tissue inflammation, Prevotella intermedia and Fusobacterium nucleatum are distinguished. These microorganisms actively colonize the gingival sulcus, maintaining a local infectious process that, if left untreated, can progress to periodontitis.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Morphological features of filamentous and flagellated forms of bacteria in the subgingival zone
• Specifics of immunopathological reactions during the destruction of periodontal collagen
• The role of concomitant flora (enterobacteria, staphylococci) in maintaining chronic periodontitis
• Mechanisms of microorganism adhesion during dental plaque formation
• Interaction of Prevotella intermedia and Fusobacterium nucleatum in pericoronitis

Other topics in the «Clinical Microbiology» section

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